724 



THE VASCULAR SYSTEMS 



dura, the outlets of the parasinoidal spaces, and, at the posterior extremity of the 

 sagittal suture, veins from the pericranium, which pass through the parietal 

 foramina. Sometimes the sagittal sinus receives a twig from the nose which 

 passes through the foramen cecum. 



SUPERIOR 

 -SAGITTAl. 

 SINUS 



__. STRAIGHT 

 ""'SINUS 



.. LATERAL 



SINUS 



FIG. 502. Coronal section of the skull to show the situations and shapes of the chief sinuses. 



(Poirier and Charpy.) 



The inferior sagittal sinus (sinus falcialis, sinus sagittalis 'inferior) (Fig. 503) 

 is contained in the posterior half or two-thirds of the free margin of the falx. 

 It is of a cylindric form, increases in size as it passes backward, and terminates 

 in the straight sinus. It receives several veins from the falx cerebri, and occa- 

 sionally a few from the mesal surface of the hemispheres. 



Torcular herophili. 



Foramen cecum. 



FIG. 503. Sagittal section of the skull, showing the sinuses of the dura. 



The straight or tentorial sinus (sinus tentorii, sinus rectus) (Figs. 502 and 503) 

 is situated at the linevof iunction of the falx cerebri with the tentorium cerebelli. 



It is triangular on section, increases in size as it proceeds backward, nnH runs 

 obliquely downward and backward from the termination of the inferior sigittal 



